Vessel Including Automatic Ballast System Using Tubes

ABSTRACT

A double-hulled vessel has a ballast draft line previously set at an empty state thereof. The double-hulled vessel of the present invention comprises an outer shell formed on bottom and side portions of the vessel; an inner shell formed on bottom and side portions of the vessel within the outer shell; an air tube positioned between the inner and outer shells; and a seawater tube positioned between the inner and outer shells, wherein seawater holes are formed in the outer shell to be connected to the seawater tube, the seawater tube is capable of containing seawater to substantially fill a space between the inner and outer shells extending from the bottom portion of the vessel up to the ballast draft line of the side portion of the vessel when the vessel is not loaded with cargo, and the air tube is capable of containing air to substantially fill the space between the inner and outer shells of the bottom and side portions of the vessel when the vessel is loaded with cargo.

TECHNICAL FIELD

The present invention relates to a vessel, and more particularly, to avessel including a seawater ballast system, such as an oil tanker or anLNG tanker.

BACKGROUND ART

Generally, ballast refers to weight loaded on a vessel for thestabilization of the hull. A vessel is provided with a ballast system tominimize trim/heel phenomena and provide the vessel with stabilizationsuch that the vessel does not overturn due to wind and wave actions. Forexample, a vessel such as a cargo vessel is provided with a ballasttank. The vessel arrives at a port for loading cargo in a state wherethe ballast tank is filled with seawater. Then, the vessel is loadedwith cargo and leaves for a destination port after the seawater ballasthas been discharged to the outside.

Solid powder or solid materials with high specific gravity are sometimesused as ballast, but water is generally used because water can be easilyobtained near the vessel. Thus, most vessels include a ballast tank,i.e. a ballast system, which corresponds to a container containingseawater as a ballast material. Accordingly, vessels have also beenequipped with pumps as a means for causing the container to be filledwith seawater, and fluid devices such as pipelines for transferring theseawater to the container and valves for regulating the pipelines.

Meanwhile, mandatory rules for double-hulled vessels have been recentlyintroduced due to serious marine pollution caused by the collision orstranding of vessels. Accordingly, a ballast tank is installed in aspace between an outer shell and an inner shell defining a cargo bay.

Such a seawater ballast system for use in the conventional vessels needsto be further improved.

A vessel operates pumps and pipelines to contain ballast seawater in thevessel to a certain degree that the buoyancy influence on the entirehull can be canceled out. However, such a system has a problem thatexcessive working expenses due to frequent power loss, pump damage, theexchange of pipes and the like should be unnecessarily spent.

In addition, the seawater filled in the ballast tank of the vesselincludes many microorganisms and is carried to the next port ofdischarge in such a state. To load cargo, the filled seawater is pumpedout at the port of discharge. At this time, there is a problem that themicroorganisms included in the seawater may cause serious changes in theecological system of microorganisms living around the port of discharge.A variety of suggestions for solving the aforementioned problem havebeen provided, but they are relatively ineffective. Further, manycountries have newly establish various kinds of regulations for solvingthe aforementioned problem.

The ballast tank is easily corroded on its surface exposed to theseawater filled therein, which may make the hull weaker. Due to thiscorrosion, the painting operation of the interior of the vessel and theexchange of steel plates of the vessel should be frequently performed,which may cause a great deal of repair and maintenance costs. Further,the seawater contaminated by the corrosion may have a serious negativeinfluence on the marine environment.

In particular, it is very important that when the vessel is damaged,conventional methods cannot ensure the restoration and survival chanceof the damaged vessels. For this reason, many mandatory regulations forthe double-hull structure of vessels have been enforced. However, evenin such a case, the restoration and survival chance of the vessel arevery low, and thus, the resultant damage to the vessel is unimaginablyserious.

DISCLOSURE OF INVENTION Technical Problem

Accordingly, the present invention is conceived to solve the problems inthe prior art. An object of the invention is to provide a vessel whichhas an automatic ballast function by causing seawater holes to be openedfor the introduction of seawater into a vessel under sail without cargo,and which has little influence on seawater near a port for loading cargoby causing the seawater to naturally flow and thus preventing thepollution due to ballast water.

Another object of the present invention is to provide a vessel includinga tube for preventing introduced seawater from coming into directcontact with an inner shell of the vessel, thereby minimizing corrosionof vessel structures.

A further object of the present invention is to provide a vessel with anadditional tube used to discharge the seawater introduced into the tube.More specifically, the introduced seawater can be discharged out of thevessel by pumping compressed air into the tube. This function can beachieved by means of the weight or compression force of cargo loaded inthe vessel. That is, the object of the present invention is to provide avessel including a seawater tube and a compressed air tube whichinteract with each other.

A still further object of the present invention is to provide a vesselwith improved restoration and survival characteristics, wherein the airtube is filled with compressed air when cargo is loaded, so that theamount of seawater introduced into the vessel due to hull damage isminimized when any probable impact is applied to the side or bottom ofthe vessel.

Technical Solution

According to an aspect of the present invention for achieving theobjects, there is provided a double-hulled vessel whose ballast draftline is previously set at an empty state thereof. The double-hulledvessel of the present invention comprises an outer shell formed onbottom and side portions of the vessel; an inner shell formed on bottomand side portions of the vessel within the outer shell; an air tubepositioned between the inner and outer shells; and a seawater tubepositioned between the inner and outer shells, wherein seawater holesare formed in the outer shell to be connected to the seawater tube, theseawater tube is capable of containing seawater to substantially fill aspace between the inner and outer shells extending from the bottomportion of the vessel up to the ballast draft line of the side portionof the vessel when the vessel is not loaded with cargo, and the air tubeis capable of containing air to substantially fill the space between theinner and outer shells of the bottom and side portions of the vesselwhen the vessel is loaded with cargo.

Preferably, an opening/closing device is provided at the seawater holes.

More preferably, the space between the inner and outer shells is dividedinto a bottom tank and a side tank, the air tube includes a bottom airtube installed in the bottom tank and a side air tube installed in theside tank, and the seawater tube includes a bottom seawater tubeinstalled in the bottom tank and a side seawater tube installed in theside tank.

An air tube may be further installed in a cargo tank defined within theinner shell to be connected to at least one of the air tubes positionedbetween the inner and outer shells.

The seawater holes may be configured to supply seawater into at leasttwo partitioned spaces between the inner and outer shells.

According to another aspect of the present invention, there is provideda method for controlling a ballast draft line in a double-hulled vesselat an empty state of the vessel, comprising the steps of providing avessel including air and seawater tubes between inner and outer shells,the seawater tube being connected to a seawater hole formed on the outershell; opening the seawater hole, when the vessel is not loaded withcargo, to allow seawater to be introduced into the seawater tube for thecontrol of the ballast draft line; and supplying air into the air tube,when the vessel is loaded with cargo, to allow the seawater contained inthe seawater tube to be discharged out of the vessel.

The method of the present invention may further comprise the step ofclosing the seawater hole when the vessel is loaded with cargo.

ADVANTAGEOUS EFFECTS

According to the present invention so configured, all the objects of thepresent invention can be achieved. By using the above configuration,buoyancy is applied not to the outer shell of a vessel but to the outershell of the cargo tank of the vessel. Thus, since a desired ballastdraft line can be easily ensured, a variety of devices for introducingor discharging ballast do not have to be used. Further, since seawateris not confined in the vessel, the seawater can be freely introduced anddischarged while the vessel is sailing, whereby the contamination ofseawater or adverse effects due to the transport of microorganisms fromone port to another can be minimized. Furthermore, since the area whereseawater is brought into direct contact with the inner shell of thevessel is very small, vessel repair and maintenance costs caused by thecorrosion or painting operation of a vessel hull can be markedlyreduced. Moreover, impact on the vessel hull can be reduced even whenthe vessel is damaged at sea.

The above effects will be again described in detail. That is, the mostadvantageous effect of the present invention is that the restoration andsurvival chance of the vessel hull can be kept at a higher level evenwhen the vessel is damaged. In a case where an empty vessel is damaged,impact applied to the vessel hull is minimized because seawater can befreely introduced and discharged. In such a case, if compressed air isintroduced into air tubes and kept at a desired level, the draft line ofthe vessel hull is not substantially changed. Obviously, the draft lineis kept substantially identical to a case where the vessel hull is notdamaged.

Further, even if a vessel is damaged at a fully loaded state, the impactapplied to the hull can be absorbed by compressed air tubes. Therefore,damage to the vessel hull is minimized and seawater is not substantiallyintroduced into the vessel. There is a great advantage in maintainingthe survival and restoration of the vessel hull. That is, thepossibility that the vessel overturns or sinks can be greatly reduced.

Another effect of the present invention is that there is nocontamination of seawater caused by ballast. Since seawater is notconfined as ballast, it can be freely introduced and discharged. Thus,there is an advantage in that microorganisms in other regions have noinfluence on the marine environment at a specific region. For example,the present invention satisfies the requirements provided in theNational Invasive Species Act (P.L. 104-332) that was enacted forpreventing proliferation and invasion of organic matters into U.S.territorial waters via ballast of commercial vessels. Further, thepresent invention also solves many problems related to the aboverequirements.

A further effect of the present invention is that the cost of vesselrepair is greatly reduced because the corrosion and painting operationof the vessel hull are markedly decreased. The reason is that since theseawater tubes prevent the vessel hull from being brought into contactwith the seawater, the interior of the ballast tank can be easily keptdry.

A still further effect of the present invention is that costs due to theoperation of the ballast system can be reduced. Since the ballast tankcan be freely opened and closed, a need for the ballast system isreduced, and thus, the operation costs of the ballast system aresimilarly reduced.

A still further effect of the present invention is that efficiency ofoperating the vessel can be increased. Since a variety of cargo can becarried in turns using a cargo tank tube, the reciprocating operationcan be performed, thereby increasing profits of shipping companies andreducing ocean freight costs.

In addition, the present invention is configured in such a manner thatthe compressed air tubes connected to the seawater tubes are placed inthe ballast tank so that the seawater introduced into the ballast tankcan be forcibly discharged to the outside. If the compressed air ismaintained in the air tubes at a desired level using a compressed airsupply device, i.e. an air compressor, already installed in the vessel,the restoration and survival chance of a damaged vessel can be greatlyimproved and a lot of impact can be absorbed even when the impact isapplied to the vessel hull.

Consequently, the present invention eliminates the adverse effects ofthe existing ballast while satisfying requirements for the ballast.Therefore, inconsistent problems of existing ballast can be solved.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features will be more apparent to thoseskilled in the art through the description of the following embodimentsof the present invention with reference to the accompanying drawings.

FIG. 1 is a perspective view showing a vessel according to an embodimentof the present invention, in which a deck, an outer side shell, an innerbottom hull and an inner side shell are partially cut away.

FIG. 2 is a bottom view of the vessel of FIG. 1, in which a seawatercirculation device of the vessel is shown.

FIGS. 3 and 4 are vertical sectional views showing the vessel of FIG. 1,in which FIG. 3 shows an empty state of the vessel and FIG. 4 shows afully loaded state of the vessel.

BEST MODE FOR CARRYING OUT THE INVENTION

The hull structure of a vessel defines the outline or framework of thevessel and is commonly formed by installing long reinforcing members toa plate member. FIG. 1 shows an example of a hull structure of a vesselaccording to an embodiment of the present invention. Althoughreinforcing members are omitted and not shown in the figures herein,those skilled in the art will understand that a variety of reinforcingmembers such as a keel and a stiffener can be installed at properpositions.

Referring to FIGS. 1 and 2, a double-hulled vessel 10 of the embodimentaccording to the present invention includes a deck 12, an outer sideshell 14, and an outer bottom shell 16. Further, the vessel 10 includesan inner side shell 18 and an inner bottom shell 20 which are placedwithin the outer shells 14 and 16, respectively. The vessel 10 alsoincludes cross bulkheads 28 traversing the vessel in a lateraldirection. By means of the cross bulkheads 28, an inner space defined bythe inner shells 18 and 20 and a space defined between the inner shells18 and 20 and the outer shells 14 and 16 are partitioned. Each of thepartitioned spaces defined in the inner shells 18 and 20 becomes a cargotank 30. Further, each of the partitioned spaces defined between theinner shells 18 and 20 and the outer shells 14 and 16 is divided intotwo spaces by means of a tank bulkhead 22. The partitioned spacepositioned near the side of the vessel is called a side tank 24(referred to as a wing tank), and the partitioned space positioned nearthe bottom of the vessel is called a bottom tank 26. Meanwhile, inanother modification, the vessel may further include a wall extendingalong the centerline CL in a longitudinal direction.

Referring to FIG. 2, a plurality of seawater holes 32 are provided inthe bottom of the vessel. Each of the seawater holes 32 is connected incommon to a side seawater tube and a bottom seawater tube (to bedescried in detail later), which are prepared in the side tank 24 andthe bottom tank 26, respectively. However, the present invention is notlimited thereto. Each of the tubes may be connected to an individualseawater hole 32. An opening/closing device 35 is provided in each ofthe seawater holes 32 (see FIGS. 3 and 4). The opening/closing device ofthe present invention is not limited to those illustrated in FIGS. 3 and4, and those skilled in the art will understand that such anopening/closing device can be properly configured in a different mannerfrom those illustrated in FIGS. 3 and 4.

Referring to FIGS. 3 and 4, the side tank 24 is provided with a side airtube 34 and a side seawater tube 36. As shown in FIG. 3, the sideseawater tube 36 is preferably sized to fully fill the space of the sidetank 24 below a ballast draft line BL set to a desired design heightwhen seawater inflow is maximized. As shown in FIG. 4, the side air tube34 is preferably sized to fully fill the side tank 24 when compressedair inflow is maximized.

Furthermore, the bottom tank 26 is provided with a bottom air tube 38and a bottom seawater tube 40. As shown in FIG. 3, the bottom seawatertube 40 is preferably sized to fully fill the bottom tank 26 whenseawater inflow is maximized. As shown in FIG. 4, the bottom air tube 38is preferably sized to fully fill the bottom tank 26 when compressed airinflow is maximized.

Meanwhile, the cargo tank 30 is provided with a cargo tank air tube 42.The cargo tank air tube 42 is sized to fill the cargo tank 30 up to theballast draft line BL from the cargo tank bottom when compressed airfully fills the tube, as shown in FIG. 3. However, the present inventionis not limited thereto.

Although it has not been shown in detail in FIGS. 3 and 4, the cargotank air tube 42 is connected to the side air tube 34 and the bottom airtube 38. Thus, when the cargo tank air tube 42 is pressed by cargo, thecompressed air in the tube 42 can be moved to the side air tube 34 andthe bottom air tube 38. At this time, the air tubes are preferablyconnected to a compressed air supply device (not shown). On the otherhand, the cargo tank air tube 42 may be connected only to the bottom airtube 38, and the side air tube 34 may be connected only to thecompressed air supply device.

The tubes may be made of surface-treated materials so as to be suitablefor fluid to be filled therein or reinforced materials. The seawatertubes are made of waterproof materials. Further, the tubes may be madeby cutting materials that have low flexibility but can be easily foldedor unfolded. On the other hand, those skilled in the art will alsounderstand that the tubes may be made of materials that are flexible andcan thus be expanded or contracted.

In addition, although it has not been shown in detail herein, the vessel10 includes a water discharge device which is connected the sideseawater tube 36 and the bottom seawater tube 40. The water dischargedevice includes a separate discharge port (not shown) in addition to adischarge pipe.

Hereinafter, the operation of the ballast system of the vessel 10according to the embodiment of the present invention will be describedwith reference to FIGS. 3 and 4. In a state where cargo is not loaded ina vessel, the opening/closing devices 35 of the seawater holes 32 aremanipulated to open the seawater holes 32, as shown in FIG. 3. Then,seawater is introduced into the bottom seawater tube 40 and the sideseawater tube 36, respectively. The seawater is introduced into thebottom seawater tube 40 and almost fully fills the bottom tank 26.Further, seawater is introduced into the side seawater tube 36 andalmost fully fills the side tank 24 below the ballast draft line BL.Then, buoyancy is substantially applied to the inner shells of thevessel, and thus, the ballast draft line can be ensured. At this time,air is removed from the bottom and side air tubes 38 and 34 to the cargotank air tube 42. The air is completely discharged from the bottom airtube 38, but still remains in a space of the side air tube 34 above theballast draft line BL.

When the vessel is under sail without cargo, the seawater holes arealways open. Thus, seawater can freely flow into or out of the tubesthrough the seawater holes. Therefore, the tubes are always filled withlocal seawater where the vessel is sailing.

Next, the operation of the ballast system performed when the vessel isfully loaded with cargo will be described. First, the seawater holes areclosed. Then, if cargo such as LNG or crude oil is filled in the cargotank 30, the cargo tank air tube 42 is pressed down and the air thereinis introduced and filled into the bottom and side air tubes 38 and 34.Thus, the bottom and side tanks 26 and 24 are almost occupied by thebottom and side air tubes 38 and 34, respectively. At this time, in acase where an amount of air is not sufficient, a compressed air supplydevice (e.g., a compressed air pump) is operated to adequately supplyair into the tubes. Meanwhile, the seawater in the seawater tubes 36 and40 are discharged out of the vessel 10 through the discharge port viathe discharge pipe. This state is well shown in FIG. 4.

The present invention is not limited to the embodiment including theaforementioned hull structure of the vessel. For example, air may besupplied to the respective air tubes by means of a compressed air supplydevice (e.g., an air compressor generally installed in the vessel)without use of the cargo tank air tube. At this time, an additional airexhaust device can be used. In another modification, the bottom and sidetanks may communicate with each other, and the bottom tank may bedivided at the center thereof.

Although the present invention has been described in connection with theembodiment, it is not limited thereto. It can be understood by thoseskilled in the art that various modifications and changes can be madethereto without departing from the spirit and scope of the presentinvention and such modifications and changes fall within the scope ofthe present invention.

1. A double-hulled vessel whose ballast draft line is previously set atan empty state thereof, comprising: an outer shell formed on bottom andside portions of the vessel; an inner shell formed on bottom and sideportions of the vessel within the outer shell; an air tube positionedbetween the inner and outer shells; and a seawater tube positionedbetween the inner and outer shells, wherein seawater holes are formed inthe outer shell to be connected to the seawater tube, the seawater tubeis capable of containing seawater to substantially fill a space betweenthe inner and outer shells extending from the bottom portion of thevessel up to the ballast draft line of the side portion of the vesselwhen the vessel is not loaded with cargo, and the air tube is capable ofcontaining air to substantially fill the space between the inner andouter shells of the bottom and side portions of the vessel when thevessel is loaded with cargo.
 2. The double-hulled vessel as claimed inclaim 1, wherein an opening/closing device is provided at the seawaterholes.
 3. The double-hulled vessel as claimed in claim 1, wherein thespace between the inner and outer shells is divided into a bottom tankand a side tank, the air tube includes a bottom air tube installed inthe bottom tank and a side air tube installed in the side tank, and theseawater tube includes a bottom seawater tube installed in the bottomtank and a side seawater tube installed in the side tank.
 4. Thedouble-hulled vessel as claimed in any one of claims 1 to 3, wherein anair tube is installed in a cargo tank defined within the inner shell tobe connected to at least one of the air tubes positioned between theinner and outer shells.
 5. The double-hulled vessel as claimed in any ofclaims 1 to 3, wherein the seawater holes are configured to supplyseawater into at least two partitioned spaces between the inner andouter shells.
 6. A method for controlling a ballast draft line in adouble-hulled vessel at an empty state of the vessel, comprising thesteps of: providing a vessel including air and seawater tubes betweeninner and outer shells, the seawater tube being connected to a seawaterhole formed on the outer shell; opening the seawater hole, when thevessel is not loaded with cargo, to allow seawater to be introduced intothe seawater tube for the control of the ballast draft line; andsupplying air into the air tube, when the vessel is loaded with cargo,to allow the seawater contained in the seawater tube to be dischargedout of the vessel.
 7. The method as claimed in claim 6, furthercomprising the step of: closing the seawater hole when the vessel isloaded with cargo.